Aguilar Miguel, Rincón Francisco
Department of Biochemistry and Molecular Biology, Campus of Rabanales, University of Córdoba, E-14014-Córdoba, Spain.
J Agric Food Chem. 2007 Dec 12;55(25):10266-74. doi: 10.1021/jf072075t. Epub 2007 Nov 15.
The furthering of scientific knowledge depends in part upon the reproducibility of experimental results. When experimental conditions are not set with sufficient precision, the resulting background noise often leads to poorly reproduced and even faulty experiments. An example of the catastrophic consequences of this background noise can be found in the design of strategies for the development of solutions aimed at preventing garlic paste greening, where reported results are contradictory. To avoid such consequences, this paper presents a two-step strategy based on the concept of experimental design. In the first step, the critical factors inherent to the problem are identified, using a 2(III)(7-4) Plackett-Burman experimental design, from a list of seven apparent critical factors (ACF); subsequently, the critical factors thus identified are considered as the factors to be optimized (FO), and optimization is performed using a Box and Wilson experimental design to identify the stationary point of the system. Optimal conditions for preventing garlic greening are examined after analysis of the complex process of green-pigment development, which involves both chemical and enzymatic reactions and is strongly influenced by pH, with an overall pH optimum of 4.5. The critical step in the greening process is the synthesis of thiosulfinates (allicin) from cysteine sulfoxides (alliin). Cysteine inhibits the greening process at this critical stage; no greening precursors are formed in the presence of around 1% cysteine. However, the optimal conditions for greening prevention are very sensitive both to the type of garlic and to manufacturing conditions. This suggests that optimal solutions for garlic greening prevention should be sought on a case-by-case basis, using the strategy presented here.
科学知识的推进部分取决于实验结果的可重复性。当实验条件设置不够精确时，产生的背景噪声往往会导致实验结果难以重现，甚至出现错误。这种背景噪声带来灾难性后果的一个例子可以在旨在防止蒜酱变绿的解决方案开发策略设计中找到，其中报告的结果相互矛盾。为避免此类后果，本文提出了一种基于实验设计概念的两步策略。第一步，使用2(III)(7 - 4) 普拉凯特 - 伯曼实验设计，从七个明显关键因素（ACF）列表中识别问题固有的关键因素；随后，将如此识别出的关键因素视为待优化因素（FO），并使用博克斯 - 威尔逊实验设计进行优化，以确定系统的驻点。在分析了绿色素形成的复杂过程后，研究了防止大蒜变绿的最佳条件，该过程涉及化学和酶促反应，并且受pH值强烈影响，总体最适pH值为4.5。变绿过程中的关键步骤是从半胱氨酸亚砜（蒜氨酸）合成硫代亚磺酸盐（大蒜素）。半胱氨酸在这个关键阶段抑制变绿过程；在存在约1%半胱氨酸的情况下不会形成变绿前体。然而，防止变绿的最佳条件对大蒜类型和生产条件都非常敏感。这表明应根据具体情况，使用此处提出的策略来寻求防止大蒜变绿的最佳解决方案。
